参数资料
| 型号： | AC300030 |
| 厂商： | Microchip Technology |
| 文件页数： | 30/64页 |
| 文件大小： | 0K |
| 描述： | KIT ACOUSTIC ACCESSORY |
| 标准包装： | 1 |
| 附件类型： | 配件套件 |
| 适用于相关产品： | 杂讯抑制/回声消除库 |
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dsPIC ? DSC Acoustic Echo Cancellation Library User’s Guide
To experiment with different values of echo tail length, change the EC_ECHOTAIL
constant defined in the ec_api.h include file, rebuild EC demo.mcp , reprogram
board 1 and rerun the demo application. The demo application relays the state of
operation through the LEDs.
The amount of nonlinear processing can be increased in 6 dB steps (up to 90 dB) by
pressing SW3. It can be reduced in 6 dB steps (down to 0 dB) by pressing SW2. The
default level for most applications is 18 dB. The acoustic echo cancellation can be
reinitialized by pressing switch, S1, on the LCD side of the MEB.
3.2.4
Demonstration Code Description
The demonstration code runs on a dsPIC33E device, using the Primary Oscillator as
the clock source with the PLL set for 40 MIPS operation.
The file, main.c , contains the main function for the demo application. This main
function allocates all the variables and arrays in data memory that are needed for DCI
data buffering, as well as the blocks of data memory that need to be allocated for the
AEC library functions.
The main function calls the WM8731Init function from the AEC library, which initializes
the AEC algorithm to its default state.
The main function also calls the WM8731Init() function to initialize the DCI module,
the WM8731 codec, and the DCI interrupt. The WM8731 codec acts as a Master and
drives the serial clock and frame synchronization lines. The DCI module is set for the
multi-channel Frame Sync Operating mode, with 16-bit data words and two data words
or time slots per frame, transmit slots and two receive slots are used in this
demonstration.
Subsequently, the WM8731Start() function is used to enable the DCI module and
I 2 C module. The codec is configured for a sample rate of 8 kHz.
The UART initialization and data processing is performed by the UART2_open()
function. The UART module is configured to generate an interrupt for every byte
transmitted or received. The UART module is run at a baud rate of ~250000 bps, with
an 8-bit, no parity, 1 Stop bit data format (8-N-1). In the UART Transmit and Receive
ISR, the corresponding interrupt flag is cleared, data is either written to U2TXREG, or
read from U2RXREG and saved in a circular buffer.
The codec driver is read for a full frame of data. The contents of the coded data buffers
are copied into the nearEndIn array and the EC_apply() function from the AEC
library is called with nearEndIn as the input data frame. The nearEndIn data buffer,
which is also the output of the EC_apply function after it has been executed, is
transferred to the UART for transmission to board 2. The UART data is converted
from μ-Law to 16-bit linear and stored in farEndIn , which is the reference (echo) input
data frame to EC_apply() .
In the main loop, the value of applyAEC is read and passed to EC_apply() as the
enable flag. If applyAEC is ‘ 0 ’, the acoustic echo cancellation is still called, but the
input/output buffer is not changed. This enables the acoustic echo cancellation to
maintain adaptation to changes in echo path, while it is not enabled.
DS70134F-page 30
? 2004-2011 Microchip Technology Inc.
相关PDF资料 |
PDF描述 |
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| ACM-16 | CABLE MODULE FR3 16BIT 40-DIP |
| ACM-2X8 | ACTIVE CABLE MODULE DUAL 8 BIT |
| ACM-8 | CABLE MODULE FR3 8BIT 28/32-DIP |
| ACS9510EVB | EVALUATION BOARD FOR ACS9510 |
| ACS9550EVB | EVALUATION BOARD FOR ACS9550 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AC300031 | 制造商:Microchip Technology Inc 功能描述:ACOUSTIC ACCESSORY KIT SPEECH RECOGNITION - Boxed Product (Development Kits) 制造商:Microchip Technology Inc 功能描述:SPEECH RECOGNIZE KIT ACOUSTIC |
| AC3000-52 | 制造商:GE Energy (formerly Lineage Power) 功能描述:Front-End Power Supply 制造商:Lineage Power 功能描述:Front-End Power Supply |
| AC3000A | 制造商:Black Box Corporation 功能描述:HD VIEW TRANSMITTER |
| AC3000A-R2 | 制造商:Black Box Corporation 功能描述:HD VIEW TRANSMITTER |
| AC3000A-R2-W1 | 制造商:Black Box Corporation 功能描述:1 YEAR WARRANTY FOR AC3000A-R2 |
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